fix(rectification): fail-close snapshot fingerprints without rewinding discrimination

Missing evidence fingerprints are stale, not current. Stale snapshots keep asking discriminators when a probe exists, and offer-candidates refuses until the ledger matches.

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/BUG_HISTORY.md

@@ -6365,6 +6365,22 @@
 - 复发自：无
 - 修复版本：待发布
 
+## BUG-420 | 候选快照缺指纹被当成 current，stale 时把区分打回采集
+
+- 状态：resolved
+- 首次发现：2026-08-28
+- 最近更新：2026-08-28
+- 影响面：`decideFromDossier`、`scoreableSnapshotIsCurrent`、`decideRectification`、GET/工具 `candidate_snapshot`
+- 用户现象：已进入区分的 Case 在快照过期或缺证据指纹时，下一问变回采集，点选卡消失。工具侧和 dossier 侧对同一份账本可能一个判 stale、一个判 current。
+- 触发条件：已有区分探针和训练门；`latest_result` 缺少 `evidence_ledger_fingerprint`，或账本指纹已变但决策器仍走 `snapshotCurrent === false → collect`。
+- 根因：dossier 用 `!storedFingerprint || stored === current` fail-open；工具用 `!storedSnapshot || !fingerprint || scoreableSnapshotIsCurrent` 同样 fail-open。`decideRectification` 把 `snapshotCurrent === false` 与方法覆盖缺失绑在一起打回 `event_collection`。
+- 修复：两处都走 `candidateSnapshotSource` + `storedSnapshotIsCurrent`。指纹缺失判 `fingerprint_missing`，不得当 current。没有已存快照仍不算 stale。快照 stale 且仍有区分探针时保持 `ask_candidate_discriminator`，receipt 写 `stale_reason`，要求重算；不把区分打回采集。不改 Skill。
+- 验证：`rectification-decide-next-action` 锁定缺指纹为 stale；训练已开+探针时 `snapshotCurrent: false` 仍是 `ask_candidate_discriminator`；训练未开仍采集。`rectification-decision-authority` 无指纹的事业/感情训练账本仍区分。`rectification-eight-method` 锁定缺指纹拒绝 `offer-candidates`；暂停逃生口和覆盖后的 34/33/33 平局只在指纹匹配时出牌。
+- 防复发：不得把空指纹写成 current。不得在已有区分探针时用 stale 快照把 `nextAction` 改成 `ask_fact_collection`。不得为了暂停出牌或平局出牌把空指纹 fail-open。`occupation_note` 仍不得单独让 scoreable 快照失效。
+- 相关记录：BUG-410、#40
+- 复发自：无
+- 修复版本：待发布
+
 ## BUG-410 | 训练已齐仍因家人/职业方法层停在采集，Agent 只确认后截断
 
 - 状态：resolved

frontend/src/lib/rectification-agentic/core/rectification-decision.ts

@@ -113,14 +113,19 @@ export function decideRectification(input: DecideRectificationInput): Rectificat
   const canDiscriminateDespiteCoverage = Boolean(probe)
     && !separation.sufficient
     && input.trainingGateOpen !== false;
-  if (
-    ((!input.methodCoverageAll && !canDiscriminateDespiteCoverage)
-      || input.trainingGateOpen === false
-      || input.snapshotCurrent === false)
-    && !(userStopped && input.candidateScores.length > 0)
-  ) {
+  const coverageBlocks = (!input.methodCoverageAll && !canDiscriminateDespiteCoverage)
+    || input.trainingGateOpen === false;
+  if (coverageBlocks && !(userStopped && input.candidateScores.length > 0)) {
     return collect(separation, holdout, range, probe);
   }
+  if (input.snapshotCurrent === false) {
+    if (probe && !userStopped && input.trainingGateOpen !== false) {
+      return discriminate(separation, holdout, range, probe);
+    }
+    if (!(userStopped && input.candidateScores.length > 0)) {
+      return collect(separation, holdout, range, probe);
+    }
+  }
   if (!separation.sufficient) {
     if (probe && !userStopped) {
       return discriminate(separation, holdout, range, probe);

frontend/src/lib/rectification-agentic/core/snapshot-source.ts

@@ -15,13 +15,15 @@ export type SnapshotStaleReason =
   | "birth_profile_changed"
   | "scoreable_evidence_changed"
   | "candidate_set_superseded"
-  | "inference_revision_changed";
+  | "inference_revision_changed"
+  | "fingerprint_missing";
 
 export const SNAPSHOT_STALE_COPY: Readonly<Record<SnapshotStaleReason, string>> = {
   birth_profile_changed: "出生资料已变化，候选已失效",
   scoreable_evidence_changed: "可评分证据已变化，请重新比较候选",
   candidate_set_superseded: "已有更新的候选结果",
   inference_revision_changed: "候选后验已更新，请使用当前结果",
+  fingerprint_missing: "候选快照缺少证据指纹，请重新比较候选",
 };
 
 export function classifySnapshotStaleReason(
@@ -29,6 +31,9 @@ export function classifySnapshotStaleReason(
   current: CandidateSnapshotSource,
 ): SnapshotStaleReason | null {
   if (!snapshot) return "candidate_set_superseded";
+  if (!snapshot.scoreableEvidenceFingerprint || !current.scoreableEvidenceFingerprint) {
+    return "fingerprint_missing";
+  }
   if (
     snapshot.birthProfileFingerprint
     && current.birthProfileFingerprint
@@ -54,11 +59,21 @@ export function scoreableSnapshotIsCurrent(
   current: CandidateSnapshotSource,
 ): boolean {
   if (!snapshot) return false;
+  if (!snapshot.scoreableEvidenceFingerprint || !current.scoreableEvidenceFingerprint) return false;
   return snapshot.scoreableEvidenceFingerprint === current.scoreableEvidenceFingerprint
     && snapshot.candidateSetVersion === current.candidateSetVersion
     && snapshot.inferenceRevision === current.inferenceRevision;
 }
 
+/** No stored snapshot is not stale; a stored snapshot with a missing fingerprint is. */
+export function storedSnapshotIsCurrent(
+  snapshot: CandidateSnapshotSource | null | undefined,
+  current: CandidateSnapshotSource,
+): boolean {
+  if (!snapshot) return true;
+  return scoreableSnapshotIsCurrent(snapshot, current);
+}
+
 export function snapshotIsCurrent(
   snapshot: CandidateSnapshotSource | null | undefined,
   current: CandidateSnapshotSource,

frontend/src/lib/rectification-agentic/v9/decision-from-dossier.ts

@@ -37,6 +37,11 @@ import {
 } from "./evidence-model";
 import { refinementFromDecisionReceipt } from "./refinement-packet";
 import { windowScanFromDecisionReceipt } from "./varga-observations";
+import { evidenceLedgerFingerprint } from "./tool-service";
+import {
+  candidateSnapshotSource,
+  storedSnapshotIsCurrent,
+} from "../core/snapshot-source.ts";
 
 export type DecisionDossier = Readonly<{
   evidence: readonly Readonly<{
@@ -75,6 +80,8 @@ export type DecisionDossier = Readonly<{
     representativeTime?: string | null;
     evidenceLedgerFingerprint?: string | null;
     candidateRangeFingerprint?: string | null;
+    policyVersion?: string | null;
+    algorithmVersion?: string | null;
   } | null;
   case: {
     acceptedTime: string | null;
@@ -249,6 +256,29 @@ function contrastPacketFromState(state: InferenceState): CandidateContrastPacket
   });
 }
 
+function scoreableSnapshotCurrentFromDossier(
+  dossier: DecisionDossier,
+  options: { currentEvidenceFingerprint?: string | null } | undefined,
+  inference: ReturnType<typeof previousInferenceFromReceipt>,
+): boolean {
+  const latest = dossier.latestResult;
+  if (!latest) return true;
+  const stored = candidateSnapshotSource({
+    birthProfileFingerprint: latest.candidateRangeFingerprint ?? "",
+    scoreableEvidenceFingerprint: latest.evidenceLedgerFingerprint ?? "",
+    inferenceRevision: inference?.revision ?? 0,
+    candidateSetVersion: inference?.candidate_set_id ?? latest.resultId ?? "",
+    scoringPolicyVersion: String(latest.policyVersion ?? latest.algorithmVersion ?? ""),
+  });
+  const currentFingerprint = options?.currentEvidenceFingerprint
+    ?? evidenceLedgerFingerprint(dossier.evidence as never);
+  const current = candidateSnapshotSource({
+    ...stored,
+    scoreableEvidenceFingerprint: currentFingerprint ?? "",
+  });
+  return storedSnapshotIsCurrent(stored, current);
+}
+
 export function decideFromDossier(
   dossier: DecisionDossier,
   options?: { currentEvidenceFingerprint?: string | null },
@@ -260,10 +290,8 @@ export function decideFromDossier(
     declinedTopics: dossier.conversationSummary.declinedSkippedTopics,
     sessionOutcome: "collect_evidence",
   });
-  const storedFingerprint = dossier.latestResult?.evidenceLedgerFingerprint ?? "";
-  const currentFingerprint = options?.currentEvidenceFingerprint ?? storedFingerprint;
-  const snapshotCurrent = !storedFingerprint || storedFingerprint === currentFingerprint;
   const latest = dossier.latestResult;
+  const snapshotCurrent = scoreableSnapshotCurrentFromDossier(dossier, options, inference);
   const confirmationGate = buildConfirmationGate({
     engineConfirmationAllowed: latest?.confirmationAllowed === true,
     candidates: (latest?.candidates ?? []).map((candidate) => ({

frontend/src/mastra/rectification-v9-tools.ts

@@ -109,7 +109,7 @@ import { offerSessionKinds } from "@/lib/rectification-agentic/core/decide-next-
 import {
   candidateSnapshotSource,
   classifySnapshotStaleReason,
-  scoreableSnapshotIsCurrent,
+  storedSnapshotIsCurrent,
   SNAPSHOT_STALE_COPY,
 } from "@/lib/rectification-agentic/core/snapshot-source";
 import type { HoldoutValidationStatus } from "@/lib/rectification-agentic/core/decide-next-action";
@@ -253,9 +253,7 @@ function safeCaseProjection(
   const separation = evaluateCandidateSeparation(candidateScores);
   const currentSnapshot = snapshotSourceFromDossier(dossier, compute);
   const storedSnapshot = latest ? storedSnapshotSource(latest) : null;
-  const snapshotCurrent = !storedSnapshot
-    || !storedSnapshot.scoreableEvidenceFingerprint
-    || scoreableSnapshotIsCurrent(storedSnapshot, currentSnapshot);
+  const snapshotCurrent = storedSnapshotIsCurrent(storedSnapshot, currentSnapshot);
   const collectingPlan = buildMethodFollowupPlan({
     evidence: dossier.evidence,
     activeFocus: dossier.conversationSummary.activeFocus,
@@ -1886,8 +1884,7 @@ export function createRectificationV9Tools(ctx: RectificationV9Context) {
         const candidateScores = candidateScoresFromLatest(latest);
         const currentSnapshot = snapshotSourceFromDossier(parsed, null);
         const storedSnapshot = storedSnapshotSource(latest);
-        const scoreableCurrent = !storedSnapshot.scoreableEvidenceFingerprint
-          || scoreableSnapshotIsCurrent(storedSnapshot, currentSnapshot);
+        const scoreableCurrent = storedSnapshotIsCurrent(storedSnapshot, currentSnapshot);
         if (!scoreableCurrent) {
           throw new RectificationToolServiceError("offer_not_allowed");
         }

frontend/tests/rectification-decide-next-action.test.ts

@@ -16,6 +16,7 @@ import {
   classifySnapshotStaleReason,
   scoreableSnapshotIsCurrent,
   snapshotIsCurrent,
+  storedSnapshotIsCurrent,
   type CandidateSnapshotSource,
 } from "../src/lib/rectification-agentic/core/snapshot-source.ts";
 import { evidenceLedgerFingerprint } from "../src/lib/rectification-agentic/v9/tool-service.ts";
@@ -461,6 +462,43 @@ test("stale reasons distinguish birth profile from scoreable evidence", () => {
   );
 });
 
+test("missing scoreable fingerprint is stale, not current", () => {
+  const current = source();
+  assert.equal(scoreableSnapshotIsCurrent(source({ scoreableEvidenceFingerprint: "" }), current), false);
+  assert.equal(scoreableSnapshotIsCurrent(current, source({ scoreableEvidenceFingerprint: "" })), false);
+  assert.equal(
+    classifySnapshotStaleReason(source({ scoreableEvidenceFingerprint: "" }), current),
+    "fingerprint_missing",
+  );
+  assert.equal(storedSnapshotIsCurrent(null, current), true);
+  assert.equal(storedSnapshotIsCurrent(source({ scoreableEvidenceFingerprint: "" }), current), false);
+  assert.equal(storedSnapshotIsCurrent(current, current), true);
+});
+
+test("stale snapshot keeps discrimination instead of returning to collection", () => {
+  const next = decideNextAction({
+    methodCoverageAll: true,
+    trainingGateOpen: true,
+    snapshotCurrent: false,
+    candidateScores: TIED,
+    discriminatorProbe: CONTRAST_PROBE,
+  });
+  assert.equal(next.type, "ask_candidate_discriminator");
+  assert.equal(decideRectification({
+    methodCoverageAll: true,
+    trainingGateOpen: true,
+    snapshotCurrent: false,
+    candidateScores: TIED,
+    discriminatorProbe: CONTRAST_PROBE,
+  }).sessionOutcome, "discriminate_candidates");
+  assert.equal(decideNextAction({
+    methodCoverageAll: false,
+    trainingGateOpen: false,
+    snapshotCurrent: false,
+    candidateScores: TIED,
+  }).type, "ask_fact_collection");
+});
+
 test("34/33/33 is a tie, not a recommended winner", () => {
   const separation = evaluateCandidateSeparation(TIED);
   assert.equal(separation.status, "not_separated");

frontend/tests/rectification-eight-method.test.ts

@@ -255,6 +255,72 @@ const careerEvidence = {
   created_at: "2026-08-12T10:00:09.000Z",
 };
 
+const methodCoverageTieEvidence = [
+  { ...educationEvidence, domain: "education" },
+  {
+    id: "44444444-4444-4444-8444-444444444442",
+    source_turn_id: TURN_ID,
+    subject: "self",
+    event_kind: "relationship_start",
+    domain: "relationship",
+    occurred_from: "2018-01-01",
+    occurred_to: null,
+    date_precision: "year",
+    summary: "感情变化",
+    status: "confirmed",
+    supersedes_evidence_id: null,
+    created_at: "2026-08-12T10:00:07.000Z",
+  },
+  {
+    id: "44444444-4444-4444-8444-444444444443",
+    source_turn_id: TURN_ID,
+    subject: "self",
+    event_kind: "career_entry",
+    domain: "career",
+    occurred_from: "2019-01-01",
+    occurred_to: null,
+    date_precision: "year",
+    summary: "工作变化",
+    status: "confirmed",
+    supersedes_evidence_id: null,
+    created_at: "2026-08-12T10:00:08.000Z",
+  },
+  {
+    id: "44444444-4444-4444-8444-444444444446",
+    source_turn_id: TURN_ID,
+    subject: "self",
+    event_kind: "family_event",
+    domain: "family",
+    occurred_from: "2020-01-01",
+    occurred_to: null,
+    date_precision: "year",
+    summary: "家人变化",
+    status: "confirmed",
+    supersedes_evidence_id: null,
+    created_at: "2026-08-12T10:00:09.000Z",
+  },
+  {
+    id: "44444444-4444-4444-8444-444444444445",
+    source_turn_id: TURN_ID,
+    subject: "self",
+    event_kind: "occupation_note",
+    domain: "occupation",
+    occurred_from: null,
+    occurred_to: null,
+    date_precision: "unknown",
+    summary: "长期一直是程序员",
+    status: "confirmed",
+    supersedes_evidence_id: null,
+    created_at: "2026-08-12T10:00:10.000Z",
+  },
+];
+
+function scoreableFingerprintForRawEvidence(evidence: unknown[]): string {
+  const parsed = parseV9CaseDossier(dossierFixture({ evidence }));
+  assert.ok(parsed);
+  return evidenceLedgerFingerprint(parsed.evidence);
+}
+
 function stubEngine(response: unknown) {
   const previous = globalThis.fetch;
   globalThis.fetch = (async () => ({
@@ -2690,6 +2756,7 @@ test("offer-candidates refuses while method coverage remains", async () => {
       latestResult: candidateSnapshotFixture({
         selectionAllowed: true,
         representativeTime: "04:48",
+        evidenceLedgerFingerprint: scoreableFingerprintForRawEvidence([educationEvidence]),
         candidates: [
           { candidate_id: CANDIDATE_ID, rank: 1, time: "04:48", relative_support: 58, tied_minute_count: 1 },
           { candidate_id: SECOND_CANDIDATE_ID, rank: 2, time: "04:49", relative_support: 42, tied_minute_count: 2 },
@@ -2727,7 +2794,7 @@ test("paused case with selection_allowed may offer the escape hatch", async () =
       latestResult: candidateSnapshotFixture({
         selectionAllowed: true,
         representativeTime: "04:48",
-        evidenceLedgerFingerprint: null,
+        evidenceLedgerFingerprint: scoreableFingerprintForRawEvidence([educationEvidence]),
         candidates: [
           { candidate_id: CANDIDATE_ID, rank: 1, time: "04:48", relative_support: 58, tied_minute_count: 1 },
           { candidate_id: SECOND_CANDIDATE_ID, rank: 2, time: "04:49", relative_support: 42, tied_minute_count: 2 },
@@ -2781,6 +2848,37 @@ test("paused case with selection_allowed may offer the escape hatch", async () =
   );
 });
 
+test("offer-candidates refuses a stored snapshot with a missing fingerprint", async () => {
+  const accounting = fakeAccounting({
+    ...receiptHandlers,
+    get_agentic_rectification_case_dossier: () => dossierFixture({
+      status: "paused",
+      evidence: [educationEvidence],
+      latestResult: candidateSnapshotFixture({
+        selectionAllowed: true,
+        representativeTime: "04:48",
+        evidenceLedgerFingerprint: null,
+        candidates: [
+          { candidate_id: CANDIDATE_ID, rank: 1, time: "04:48", relative_support: 58, tied_minute_count: 1 },
+          { candidate_id: SECOND_CANDIDATE_ID, rank: 2, time: "04:49", relative_support: 42, tied_minute_count: 2 },
+        ],
+      }),
+    }),
+  });
+  const tools = createRectificationV9Tools({
+    userId: USER_ID,
+    caseId: CASE_ID,
+    turnId: TURN_ID,
+    accounting: accounting.client as never,
+  });
+  await assert.rejects(
+    () => (tools["rectification-offer-candidates"] as unknown as {
+      execute(input: unknown): Promise<unknown>;
+    }).execute({ caseId: CASE_ID }),
+    (error: unknown) => error instanceof RectificationToolServiceError && error.code === "offer_not_allowed",
+  );
+});
+
 test("paused case resumes only when the Agent explicitly requests it", async () => {
   let reads = 0;
   const accounting = fakeAccounting({
@@ -2819,69 +2917,11 @@ test("offer-candidates allows a 34/33/33 tie after method coverage when remainin
   const accounting = fakeAccounting({
     ...receiptHandlers,
     get_agentic_rectification_case_dossier: () => dossierFixture({
-      evidence: [
-        { ...educationEvidence, domain: "education" },
-        {
-          id: "44444444-4444-4444-8444-444444444442",
-          source_turn_id: TURN_ID,
-          subject: "self",
-          event_kind: "relationship_start",
-          domain: "relationship",
-          occurred_from: "2018-01-01",
-          occurred_to: null,
-          date_precision: "year",
-          summary: "感情变化",
-          status: "confirmed",
-          supersedes_evidence_id: null,
-          created_at: "2026-08-12T10:00:07.000Z",
-        },
-        {
-          id: "44444444-4444-4444-8444-444444444443",
-          source_turn_id: TURN_ID,
-          subject: "self",
-          event_kind: "career_entry",
-          domain: "career",
-          occurred_from: "2019-01-01",
-          occurred_to: null,
-          date_precision: "year",
-          summary: "工作变化",
-          status: "confirmed",
-          supersedes_evidence_id: null,
-          created_at: "2026-08-12T10:00:08.000Z",
-        },
-        {
-          id: "44444444-4444-4444-8444-444444444446",
-          source_turn_id: TURN_ID,
-          subject: "self",
-          event_kind: "family_event",
-          domain: "family",
-          occurred_from: "2020-01-01",
-          occurred_to: null,
-          date_precision: "year",
-          summary: "家人变化",
-          status: "confirmed",
-          supersedes_evidence_id: null,
-          created_at: "2026-08-12T10:00:09.000Z",
-        },
-        {
-          id: "44444444-4444-4444-8444-444444444445",
-          source_turn_id: TURN_ID,
-          subject: "self",
-          event_kind: "occupation_note",
-          domain: "occupation",
-          occurred_from: null,
-          occurred_to: null,
-          date_precision: "unknown",
-          summary: "长期一直是程序员",
-          status: "confirmed",
-          supersedes_evidence_id: null,
-          created_at: "2026-08-12T10:00:10.000Z",
-        },
-      ],
+      evidence: methodCoverageTieEvidence,
       latestResult: candidateSnapshotFixture({
         selectionAllowed: true,
         representativeTime: "05:00",
-        evidenceLedgerFingerprint: null,
+        evidenceLedgerFingerprint: scoreableFingerprintForRawEvidence(methodCoverageTieEvidence),
         decisionReceipt: {
           propose_allowed: true,
           window_scan: {